One young girl suffered a spinal cord injury and was being transferred to neighbouring Tunisia for treatment, her father told the BBC.

The blast took place in a small side street and left a scene of devastation, the BBC's Rana Jawad in Tripoli reports.

As well as extensive damage to the embassy building and perimeter wall, two nearby homes were badly damaged and others affected, while the windows of a shop were blown out and two parked cars were burnt out.

Many neighbours who gathered in the street to survey the damage were shaken and upset by what had happened, our correspondent says.

They told her that there was a lack of proper policing for such a potentially high-profile target.

Analysis

By Rana JawadBBC News, Tripoli

It was an unfamiliar scene in the Libyan capital's upscale residential neighbourhood - and left many breathless and confused, unsure of how to react.

First came the tears of a young 15-year-old, shocked by the impact of the blast just metres from his now partially wrecked home.

His uncle stood on a pile of concrete rubble in their courtyard. "You can't even fix the water, look!" he shouted at military personnel who were telling people to stay back as the street flooded from a pipe that had burst as a result of the explosion.

Another man sat silently amidst the debris on the floor of the house next door, framed by what was left standing of the blasted concrete.

Many questions are reverberating across Tripoli. People know what has happened, but they don't understand why, or who did it.

These are the answers they will be demanding of their officials, who are still reeling from the complex network of armed groups that have emerged since the war, as they try to rebuild the nation's security apparatus.

Unless they get lucky, these officials are unlikely to be able to deliver the answers anytime soon.

"It was a big mistake to site the French embassy in our neighbourhood," a local resident said.

President Hollande said the attack had targeted "all countries in the international community engaged in the fight against terrorism".

"France expects the Libyan authorities to shed the fullest light on this unacceptable act, so that the perpetrators are identified and brought to justice," he said.

French Foreign Minister Laurent Fabius - who has arrived in Libya to see for himself the damage - said French officials would work closely with the Libyan authorities to find out who was responsible for what he called an "odious act".

Libyan Foreign Minister Mohammed Abdel Aziz condemned the bombing as a "terrorist act", but did not speculate on who might be behind it.

No group has yet claimed responsibility for the attack.

French embassies across northern Africa have been on high alert since France sent in troops to help fight an Islamist insurgency in Mali in January.

France, under Nicolas Sarkozy, was at the forefront of Nato-led air strikes in 2011 that helped rebel forces topple long-time Libyan leader Muammar Gaddafi.

The US consulate in the eastern city of Benghazi was attacked by armed men in September 2012, leading to the killing of ambassador Christopher Stevens and three other American officials.